This invention relates generally to aircraft environmental control systems and more particularly to a novel modular air shut-off valve for controlling airflow within an aircraft cooling air duct.
The environmental control systems of certain aircraft, though designed to provide wholly adequate cooling airflow, during flight, to the cockpit and to radar and various avionic systems, may not be designed to provide sufficient cooling to all systems while the aircraft is on the ground on a hot day. It is recognized, however, that when the aircraft is awaiting takeoff, certain systems aboard the aircraft may not need to be fully functional. For example, when the aircraft is on the ground, the radar on board may function only in a standby mode, requiring less than full cooling airflow rates to all portions of the radar system, and therefore the cooling airflow to some portions thereof may be closed off during this period. The capability to control the flow of cooling air as just stated may be essential in order to meet hot-day ground operational requirements of the aircraft.
The present invention provides a modular air shut-off valve for use in the ducts which supply coling air within the environmental control system of an aircraft. The valve has found particular application to control the flow of coolant air to the radar in ground operation modes aboard the aircraft to satisfy specifications for hot-day ground operation. The valve of the present invention comprises a generally rectangularly-shaped vane or damper, mounted on a rotatable shaft within a suitable housing in an air conditioning duct, and having flexible marginal portions contacting the inner surfaces of the housing in the closed position. The vane may therefore be self-adjusting and may serve as a relief valve in the event of overpressure in the duct containing the valve. In the specific embodiment described herein to illustrate a representative structure and built to demonstrate utility of the invention, the valve was configured to control the flow of cooling air to the radar system; the valve was controlled pneumatically using the servo air (about 18 psig) provided by the aircraft for the pressurization of the waveguide; power to the pneumatic system controlling the valve was provided by a 28-volt signal from a squat switch on the landing gear of the aircraft.
It is therefore a principal object of the present invention to provide a modular air shut-off valve.
It is a further object to provide a modular air control valve particularly useful within the environmental control system of an aircraft.
These and other objects of the present invention will become apparent as the detailed description of specific representative embodiments thereof proceeds.